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UBC Theses and Dissertations

A quantitative evaluation of porcupine-habitat relationships in the Kalum Valley, B. C. Lawson, Andrea L


The implications that the interactions between animals and the communities in which they exist have to wildlife management are just being realized. The assessment of species-habitat interactions necessitates the consideration of many variables and the adaptation of multivariate statistics to ecology has made possible the multidimensional consideration of habitats. The purpose of this thesis is to evaluate the usefulness of a multivariate approach to an applied management problem: porcupine-habitat interactions in the Kalum Valley B.C. In recent years an alarming amount of damage caused by the winter feeding of porcupines has been occurring on the north coast of B.C. There is concern that silvicultural practices, such as thinning of croptrees, are predisposing stands to attack. The three specific objectives addressed in this thesis are: 1) To test the hypothesis that thinned stands incur more damage than unthinned stands 2) To investigate the process by which porcupines are selecting habitats and individual trees 3) To determine the variable or combination of variables that best predicts damage. Four 100 ha. blocks of forest were selected in the Kalum Valley.Two stands had been spaced and two were unmanaged. Within these stands 25 sampling plots were randomly selected. Three sets of variables were recorded in each plot: recent and past porcupine damage to trees, % cover of all species of vegetation, % cover of vegetation strata. The results indicate that thinned stands do not incur more damage than unthinned stands. In fact, unthinned stands incur more new damage than do spaced areas, indicating that porcupines demonstrate choice at the level of large blocks of forest perhaps on the basis of stand properties such as density or basal area of trees. Hemlock was almost exclusively attacked with damage peaking in the 20.1-20.5 diameter class. Within stands, damage is not related to density, basal area of trees or any site features at the level of the plot except the number of stumps. Damage is related to the cover of a few herbs. This result is probably related tothe greater amounts of light reaching the forest floor in damaged areas resulting from the dead tops of the hemlock trees. Thus, damage is predictable from the individual tree characteristics of species and diameter class of trees. Trees in unthinned areas appear to be more likely to incur damage.

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